html{
    height: 100%;
}
body{
    /* height: 100vh */
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100%;
}
#wrapBg{
    width: 343px;
    height: 480px;
    background-image: url("../img/bg.jpg");
    position: relative;
    overflow: hidden;
}
#headTitle{
    width: 236px;
    height: 77px;
    background-image: url("../img/head.jpg");
    background-repeat: no-repeat;
    position: absolute;
    left: 53px;
    top: 100px;
}
#headBird{
    float: right;
    margin-top: 25px; 
}
#startBtn{
    width: 85px;
    height: 29px;
    background-image: url("../img/start.jpg");
    position: absolute;
    left: 50%;
    top: 250px;
    /* margin-left: -43px; */
    transform: translateX(-50%);
    /*当容器大小不为定值时可使用*/
}

#grassLand1{
    
    width: 343px;
    height: 14px;
    background-image: url("../img/banner.jpg");
    position: absolute; 
    left: 0px;
    top: 423px; 
}
#grassLand2{
    
    width: 343px;
    height: 14px;
    background-image: url("../img/banner.jpg");
    position: absolute;
     left: 343px; 
    top: 423px; 
}